Ferricytochrome c

作者：Richard E. Dickerson, Tsunehiro Takano, David S Eisenberg, Olga B. Kallai, Lalli Samson, Angela Cooper, E. Margoliash · 发表于：Journal of Biological Chemistry · 年份：1971 · DOI：10.1016/s0021-9258(19)77002-1 · 被引用次数：877 · 研究领域：Photosynthetic Processes and Mechanisms、Hemoglobin structure and function、Mass Spectrometry Techniques and Applications

The structure of crystalline horse heart ferricytochrome c has been determined by x-ray methods to a resolution of 2.8 A, and the results have been extended to obtain the structure of bonito cytochrome c as well. There is no difference between the horse and bonito structures, other than the expected changes in side chains where the amino acid sequences differ. The tertiary folding of cytochrome c has been maintained constant since the ancestors of mammals and fish diverged 400 million years ago, and probably for much longer. The polypeptide chain of 104 amino acids is wrapped around the heme in two halves; residues 1 to 47 to the right and 48 to 91 to the left of the heme, which sits in the resultant heme crevice with one edge exposed to solvent. Residues 92 to 104 form an α helical strap that rises over the top rear of the molecule and back across the right side again. Cysteines 14 and 17 and histidine 18 extend to the heme from the right wall of the heme crevice, and methionine 80 extends from the left wall. The heme is tightly enveloped in hydrophobic groups. Two channels filled with hydrophobic side chains lead to the right and left from the heme to the surface of the molecule. Each channel contains at least two aromatic rings in roughly parallel orientation, and each channel is surrounded by a cluster of positively charged lysines where it meets the surface. At the back rear of the molecule, between the two positive regions, is a cluster of nine negatively charged acidic...